A Houston ninth grader needed several stitches in her arm Monday after being stabbed by an apparent homeless man.

Other students helped detain the suspect for police after the assault outside Lamar High School just before classes started Monday.

The man is expected to face assault charges.

Catherine Sullivan, 14, said she was standing with some friends when a man approached and attacked her using two knives.

Sullivan said she tried to protect herself by holding her arm in front of the man. The girl suffered several cuts.

Principal James McSwain described the man as a "mentally ill individual" in his 40s.